In wireless communication systems, RRM is generally responsible for utilizing the air interface resources. RRM is used to guarantee quality of service (QoS), to provide efficient use of the radio resources, and to increase system capacity. RRM consists of admission control, handover, power control, and congestion control functionalities. Admission control can be divided into user admission control and call admission control (CAC). User admission control accepts or rejects the radio resource control (RRC) connection requested by a wireless transmit/receive unit (WTRU). Call admission control accepts or rejects a request to establish or modify a radio access bearer (RAB) in the radio access network (RAN). Call admission control is located in the controlling radio network controller (C-RNC).
There are two dynamic channel allocation (DCA) functions, slow DCA and fast DCA (S-DCA, F-DCA). The S-DCA allocates the radio resources to cells while the F-DCA allocates the radio resources to bearer service. The F-DCA call admission control functions are responsible for efficiently allocating or changing the allocations of physical resources. When a request for physical resources is received, the call admission control will accept or reject the request based on the availability of physical resources and interference level in the cell. The request can be accepted only if both uplink and downlink call admission control admit it. Otherwise, the request is rejected.
Handover is used to switch a radio link from one cell to another without interruption of the call in order to maintain the required QoS. The radio link addition procedure is used to establish physical resources for a new radio link in a Node B for which a WTRU already has a communication context when a handover is taking place.
In order to guarantee the QoS and minimize the interference, a certain F-DCA call admission control algorithm is currently implemented. But the previous implementation of the F-DCA call admission control algorithm has several limitations. One limitation is that it is difficult to be reused by other RRM functions since the main interface function is large, and the inputs to the code allocation function (which forms the core function of the F-DCA call admission control algorithm), are dependent on the signal message. A second limitation is that the past implementation of the F-DCA CAC algorithm is generally only suitable for real time (RT) service.
It is desirable to provide an optimized implementation of the F-DCA CAC algorithm for radio link addition which is suitable for real time (RT) service and non-real time (NRT) service, and which overcomes the disadvantages of the known algorithms.